LAUSR

This study was designated to correlate protein, tannin and total phenolic content with textural features of sorghum grains from the individual color channels R, G, B, U, V, H, S, I, L, a, b, X, Y, Z. The highest correlation coefficient (R = 0.83) for protein content was observed for texture LATeta4 from channel L. The quantity of protein was not significantly correlated with any of the features from channels G, a, H and I. The highest negative correlations between textural features and tannin content were found for textures SS5SV1SumEntrp and SS5SH1SumEntrp (R = − 0.91) from channel S and the strongest positive correlation coefficients were obtained for bS5SN3AngScMom and bS5SZ1AngScMom (R = 0.86) from channel b. The tannin (%) in sorghum grains was not significantly correlated with any of the textural features from channels R, G, L, H, I, X and Y. The highest correlation for total phenolic compounds was observed from color channel S.; the highest positive one (R = 0.91) for textures SS5SZ5AngScMom, SS5SN5AngScMom, SS5SH5AngScMom and SS5SV5AngScMom and the highest negative for texture SS5SV1SumEntrp (R = − 0.95). Moreover, no statistically significant correlation between total phenolic compounds and textures from channels R, L, H, I, X and Y was determined. The quantity of protein, tannin and total phenolic compounds (%) was regressed on selected textures. The highest coefficients of determination for equations estimating protein, tannin and total phenolic compound were 0.68, 0.83 and 0.90, respectively. This study suggests image processing as an alternative approach to the laboratory methods for quantification of protein, tannin and total phenolic compounds of sorghum grain.